how exactly does metabolism slow when dieting?

[Lao Tzu]

Do you just start conserving energy w/o thinking about it by not exerting yourself anymore? i've seen studies that show when calories are cut metabolism is slowed by coercing someone to not exert themselves and to remain much more immobile. But aside from activity metabolism dropping how does base metabolic rate drop?

And is it possible to have a metabolic slowdown w/o any symptoms like lethargy, fatigue, needing more sleep, etc.

 

[danielson]

im guessing hormonal depression with cortisol raising, thyroid levels changing and test. levels changing due to the stress of dieting

i;d guess thyroid effects are most significant/will show the most through tiredness, lethargy etc....i doubt you'd get any clinical signs of hypothyroidism

 

[Lao Tzu]

hypothyroidism has a list of symptoms.

What i dont get is if the human body can function effectively on 70% of calories (as a guess) why doesn't it do that 24/7?

 

[OXANDRIN]

easy.....your body gets less fuel therefor it slows down the rate at which it uses fuel

eat a few big meals and it speeds back up

 

[Lao Tzu]

easy.....your body gets less fuel therefor it slows down the rate at which it uses fuel

eat a few big meals and it speeds back up

do you mean eat 3 big meals a day or eat at maintenance for a while? i already eat at maintenance about 5-6 days a month.

 

[danielson]

hypothyroidism has a list of symptoms.

What i dont get is if the human body can function effectively on 70% of calories (as a guess) why doesn't it do that 24/7?

yeah but my point was the clinical symptoms wouldnt necessarily all manifest themselves during dieting...also only about 2-3 symptoms are v.common, the rest are on the 'can occur'. i think you can get a slightly depressed thryoid through dieting and not have any clinical symptoms and it will effect your metabolism.

it can survive, but if it has calories coming in, its evolution has taught it to absor everything and use it if its there. science says low calk diets will have you live longer, and less calories for a sedentary person are important. but if yopur exercise level is high and long term, your calorie intake has to match or long term there will be trouble. of course short term dieting is cool

 

[OXANDRIN]

do you mean eat 3 big meals a day or eat at maintenance for a while? i already eat at maintenance about 5-6 days a month.

the idea of spreading meal apart 2-3 hours keeps the body in a state where it thinks it is getting plenty of fuel to burn


but eventually if you are in a calorie deficit your body slows down to conserve fuel.

that is where cheat meals come in. get everything up and running again

 

[sexyelbowflaps]

another thing is; you spend a lot of calories just breaking down your food, if you eat less food, you expend less calories digesting. I think i remember the number being like 20% of the calories you expend throughout the day is through digestion of food.

 

[Lao Tzu]

another thing is; you spend a lot of calories just breaking down your food, if you eat less food, you expend less calories digesting. I think i remember the number being like 20% of the calories you expend throughout the day is through digestion of food.

ive heard that too, and i've heard that 5-6 high protein meals is the best way to exploit this. However ive also heard from BBF that the body adjusts to this in a few months or so.

 

[PinkPanther]

So, will all this to keep in mind, how does one find the best amount of calories to consume in a day in order to lose fat??

 

[OXANDRIN]

calculate BMR

 

[Lao Tzu]

calculate BMR

i dont know how as i wouldn't know how to factor in things like walking, exercise, moving around, etc. And the calculators are all crap, one will say 2200, one will say 3100, one will say 2600.

 

[OXANDRIN]

i dont know how as i wouldn't know how to factor in things like walking, exercise, moving around, etc. And the calculators are all crap, one will say 2200, one will say 3100, one will say 2600.

there should be one where you can rate your activity level

 

[Lao Tzu]

there should be one where you can rate your activity level

yeah i know, most calculators come out to 2400 or so for BMR. Some say closer to 3000 like the Katch-McArdle Formula.

Either way i dont know if i trust those scales. They don't consider individual MR which can be based on a variety of things. they also ignore muscle mass. Some calculators give me an end reading (after factoring in exercise & lifestyle) of 3700, some give me 3300, some 2800.

but i think 2500 is a good estimate for my BMR.


Anyway, when i was losing weight (up until a few months ago) i was losing 2-3 lbs a week on 2800 calories a day with a moderately sedentary lifestyle (didn't have to walk around for school or do much activity) and about 180 min. of cycling a week.


If 2.5 lbs = 9000 calories/7 = 1285/day deficit on a 2800 cal diet. so my normal metabolism is around 4000 a day?